Electron discharge device of the magnetron type



May 4, 1948. J. s. DONAL, JR., 'ErAL 2,440,851

ELECTRON DISCHARGE DEVICE OE THE MAGNETRON TYPE lll/11111111111.

, Filed March 8,"1944 mi@ wcn www W 0 N A E Patent-ed May `4, 13948 .John 'S. Donal, Jr., BarremoreB. Brown, `and .CarmenLouis Cuccia,VP1-`inc`e`ton, N. 3.,as`s`ign- Vration Aof Delaware ors to Radio 'Corporation of America, a corpo- Application March s, 1944, serial .n5525515 `Our .invention .relates .to electron discharge idevices .for use .at ultra .high trednencies, and ,more particularly to magnetrons utilizing cavity resonator-circnits. f A y i In one form of a, magnetron utilizing `cavity resonators .the .electrodemoiint comprises -an anode Iblol; lhaving fa" central opening fin which a cathode isjaxially positioned. '-Radially extends claims. (ci. 'srs-39) ing slots communicating with the central opening i,

provide the cavityv resonators-the portions of 4,the block adjacent `the central ,opening and `between the slots. providing fthe .anode segments.

InV another yforni thecavity.resonators/may be bores or cylindrically shaped chambers extending i through the lanodezblocktand parallel to t'he cen'- tral opening and ,communicatingwith .the central opening.throiigh`slots` para1lel to 'the axis o'f the centralk opening, ,the portions of the .anode block adjacent the centralopening and between the `slots again providing .the anode segments.

In this typejof magnetron it `has been the usual practicejto machinet'he anode block with its re"s onant cavities .irom ,a solidblock of 'conducting material such `as copper, which may beinthe form of a cylinder, `spaces Ibeing machined atboth ends ofthe cylinder to provide roon for mounting the cathode fand catlrlode'` leads, fthe ends of the cylinder being' 'closed vlcnfucoverplates soldered or otherwise sealed to the ends-` of the cylinder to provide an envelope. `In a variation, a, sepa-v rate anode has "been foi-ined" by machining' or stamping, 'this "anode being inserted Linto a 4machined'genvelopel Vin the 'form of a hollow cylinder, end plates 'again being provided toeoinplete the envelope/i.. Vj y "The, machining lofi'thefenvelope 'and block is time-consuming and the construction described results "in, diiculty in mounting and centering of V thecathode., Usually ."xed magnets or electromagnets are utilized with the magnetrons or 'the type d1e` scribed above. Because of the longairgaps made necessary vbetween the 'electrode meent and the.

outside of 'the envelpe larger magnets 'than ide-V sired arehecessary to provides; fielderdesired` intensity. p In any magnetron, leadsrnust be em- 1 ployed to support itjhe 'cathodeand :make contact to the cathode and the cathode heater. Thesef leads usually 'pass through the space at "theends of the vanode and result inan` air gap in the magnetic circuit which is incqnveniennyiarge. itis standard :practice alsoto "weld .a metallic disc tov the "cathod'efleads Lin order tol form v'electrostatic shields at cathode potential 'at "the ends 'of'th'e cathode for preventing drift of the electrons out l2 the ends of the lanode cavity. This contributes tothe necessity `for .providing larger than vdesired airgaps. Y

It Lis, lthereforal an foh'je'ct of our invention 'to provide anump'rved .electron discharge fdevice of the magnetron' type using cavity resonator circuits and particularly useful at nltiia high "fiel .Another object "of 'our `invention .is to provide such a device of simpliii'ed design whichv will permit ready 'manufactu'reandfwhich eliminates the need for lextensivefmachining operations.

LA still further object of our inventionis to provide 'such a device having a` noveland effective support.

means for, supporting the :cathode land Aits leads and whichfacilit'ates 'mounting and 'centering of the cathode. Y

More particular-ly fit Vis an obj ect .of 'our invention toprovlde such a device in which the elec-` trode mount assembly ycan jbe .mounted on a header 'to facilitate jas'seinbly ,of the .mount and incorporation within an envelope. A further :obj ect of our invention is to provide such a device in "which the .gaps in the magnetic circuit 'are `substatially reduced, thus permitting a decrease "in the size and strength of the magnet, electromagnet or `coils for providing `a magnetic. eld `of required intensity.

A` 'furtherobje'ot of oiiri'nvent'ion is to provide a` magnetron in `which 'the 'conventional end elec.. tron shields are eliminated. K A Another speciiic'obj Yct, 'i our invention is to provide a .magnetron whichV permits pulsing `of the `anode when Athe device i's in operation, thus 35' eliminating the need fora lowgcapacitance lament transformer 'and 'still yfurther reducing the gaps in the magnetic circuit.

` The novel features whichwe believe 'to be char-` acteristic or our inventionjare set forth with particularity in the Aappendied claims, *but the invention itself will Vbest "lie iinderstood ylyreierence to the following description taken in connection with the "accompanying drawing in wnichFigu're 1 isa top view withpart of the` envelope removed showing an electrondischarge `device l:made` ac` @Ording to our linveritin, Figure 2 is s vertical iine '1r- 1I in Figure 11,

is asectiontakeii aiongtiie'iin Iv-rv efrigure 1, Figure sis .a transverse vertical :sectionttaken along lthe "line V--Vo 'ieii'ref Sand Figure f6 is a section showing details or'tneycatnode and its "In annemarie-e with turn-investi@ -we Aprovi-ae Figure 3 is a sidenewwithlisaitef` the iin-venise` removed" to Show `details ofl'constructiomfFigure 4 the anode segments.` Extending axially of the chamber I I is the indirectly heated cathode I4.

Both the anode block and cathode are supported from a header member I5 inI a manner to be described. l

Tubular members I6 and II, Vhaving one end fitting into the anode block I0, extend'through apertures in the header member I5` to Iwhich the tubular members I8, I9 are hermetically sealed,

preferably by welding to the header the anges Y I8' and I9. The outer ends `of the tubular members I5 and Il are insulatingly sealed to the end of the tubular members .I8 and I9 by means of the seals 20 and 2|.v f

. The` punched sheets forming the anode stack or block are provided with the punched-outvportions forming the passageway 22 communicating with the interior of the tubular members I6 and ITthus providing a means forcooling the anode block. .Thesetubular membersIIi` and I'I are the sole means for insulatinglysupporting the anodel block from the header member.

'On each side Vof the anode are mounted the elements or inserts of magnetic material which form part .of the magnetic circuit and also pro Vide a support for the cathode vwithinthe anode chamber II. These inserts are l'supported by means of the tubular 4or box-like structure 25 having flanges 26l and 2T secured to thelheader member I5. The cathode and anode are insulatingly supported with respect to each other.

v Themethodof supporting the cathode is shown in Figure 6. The magnetic insert 23'is"provided with a central bore through which the cathode lll'having the heater 'M' is extended, the flange I fof the cathode being secured Ato, the insert.

The end of the; insert is provided with a. groove 35fin-rwhich lie the ends of the cathode'heater.

oneend` 3'I-being-electrically connected or welded tothe insert and vthe other end ofthe cathode heater 38 extending from the `groove which is covered by means of plate member `:36. It is, of course, understood that the cathodeis coated with emitting material andfthat the. heater I4 is sprayed with the usual insulating material to .prevent short circuit within the sleeve. v

A'Ifhe end 38 of. thev heater is'l secured to a lead 39 extending through the eyelet 40 and sealed by means ofthe seal 4I thus providing` a circuit to one side of the cathode Vheater,.the other side of the heater circuit being connected through the header I5 or the envelope 28 of the tube having a lip 29 welded to the header member. Y

A fixed magnet maybe used having pole pieces 42 and 43 contacting the outer shell of the envelope and providing with they inserts 23 and 24 the magnetic circuit. Because the box-like member 2-5 is connected to the header member, the envelope 28 may contact the inserts, thus reducingthegap in the magnetic circuit. 1 y

The-load may be coupledout of the magnetron byfmeans of the coupling loop 30 extended into the internal conductor 3 I of the coaxialline comprising` conductor 3| and outer tubular member 32 sealed at its end by means of cup-shaped element 33. This coupling device may be coupled into a wave guide or resonator, the end of the 24 may be made of cold rolled steel.

4 struction is described and claimed in a copending application of Donal and Hegbar, Serial No. 496,570, filed July 29, 1943, and assigned to the same assignee as the present application.

The header member and the envelope may be made of stainless steel having non-magnetic properties so that it does not interfere with the magnetic circuit. The magnetic inserts 23 and The header may consist of an oval plate of metal of a. thickness suilicient to give suitable rigidity. In one example stainless steel .025 inch thick was employed. The tubular members I8, I9 and 49 in the form of eyelets are welded to the header to permit sealing-in of the heater and heater cathode leads and it is convenient to make the junctions of these tubular members with a header vacuum-tight by melting silver-nickel solder at these junctions in an atmosphere of chemically dried hydrogen. Other materials are equally suitable. p

The magnetic inserts eliminate the air gaps which are inconveniently large in previous magnetrons of thisV type and also eliminateV the necessity for electron shields to prevent drift of electrons from the vanode space. y

The constructionA also avoids the necessity for having separate cathode leads for supporting the cathode and shields within the anode. The spaces between the inserts and the anode may be of the order of .030 to .040 inch. 'Ihese spaces plus the thin walls of the envelope are the only air gaps'in the' magnetic circuit, except for the anode thickness. Thus no space is lost due to the thickness of a non-magnetic cathode support. Also the fact that the inserts can be varied in height, also means tubes of different anode length may be fitted into the same envelope bymerely changing the lthickness of the inserts.

As pointed out above, the advantages of the construction described which permits pulsing of the anode are, rst, that a low capacitance filament transformer is no longer necessary, and, secondly, only between the cathode support and anode need a gap for voltage clearance be left so that the support'may be at the potential of the envelope. 'I'he second condition results in a reduction of the gap between the pole faces of thel magnet and 4permits the use of a lighter magnet. A

While we have indicated the preferred embodiments of our invention ofv which We are now aware and havefalso indicated only one specific used and the purpose for which it isemploy'ed Without departing from the scope of our invention asset forth in the appended claims.

What we claim as new is:

l. An electron discharge device including a ilatV header member of conducting material, an anode block insulatingly supported .from said header member and extending'transversely thereto and having .a plurality of anode elementsV deiininga central space having a longitudinal laxis parallel to said header member, a cathode for supplying electrons within said central space, means sup-` porting said cathode including a member of magnetic material supported on said header, and an envelope enclosing said anode block, cathode and supporting means and sealed to said header memconductorv3| acting 'as a radiator. This con- 75 ber. l Y

2. An electron discharge device including a at header member of conducting material, an anode block insulatingly supported on said header member and having leads extending through and sealed to said header member, said anode block having a plurality of anode elements defining a central space, a hollow conducting member surrounding said anode block and supported by said header member, said hollow conducting member supporting an element of magnetic material on each side of said anode block registering with said central space, one of said elements of magnetic material supporting a cathode for supplying electrons within said central space, and an envelope sealed to said header member and surrounding said anode block and said hollow conducting member and having walls closely adjacent said elements of magnetic material, and magnetic means registering with said magnetic elements for providing a magnetic eld within said central space.

3. An electron discharge device having an envelope including a header of conducting material and including a cathode and an anode, a plurality of tubular members insulatingly sealed through said header and supporting said anode, said anode having a passageway therethrough, said passageway opening into said tubular members supporting said anode on said header, said tubular members and passageway providing means permitting circulation of a cooling medium through said anode.

4. An electron discharge device having an envelope including a header of conducting material, an anode electrode having a central chamber, a plurality of tubular members insulatingly sealed through said header and supporting said anode electrode, said anode having a passageway therethrough, said passageway opening into said tubular members supporting said anode on said header for providing means permitting circulation of a cooling medium through said anode, said anode being surrounded by a tubular member supported on said header, an element of magnetic material supported by said tubular member adjacent and in registry with the central chamber in said anode, and a cathode for supplying electrons within said central chamber and supported by said element of magnetic material.

5. An electron discharge device having an envelope including a header of conducting material, an anode having a plurality of anode elements dening a central space, conducting members insulatingly sealed through said header `and supporting said anode, a hollow conducting member supported on said header and surrounding said anode, an element of magnetic material supported by said hollow conducting member on each side of said anode and adjacent and in registry with said central space, and a cathode supported by one of said elements of magnetic material.

6. An electron discharge device having an envelope including a header of conducting material and an anode having a plurality of anode elements defining a central space, conducting members insulatingly sealed through said header and supporting said anode, a box-like hollow conducting member supported on said header and surrounding said anode, and an element of magnetic material on each side of said anode and supported by and extending through the walls of the box-like member toward and in registry with said central space, and a cathode supported by one of said elements of magnetic material.

'7. An electron discharge device having an envelope including a header member of at conducting material and an elongated at anode block mounted normal to said header member having a plurality of anode elements defining a central space, said header member having a plurality of apertures extending therethrough and a pair of conducting members extending through said apertures and insulatingly sealed therein to said header and connected to the ends of said anode block insulatingly supporting said anode block from said header member, and a hollow conducting member of rectangular transverse section supported on said header member and surrounding said anode, and an element of magnetic material supported by and extending through said hollow conducting member on each side of said anode and adjacent and in registry with said central space, said cathode being supported by one of said elements of magnetic material, and means external of said envelope providing with said elements of magnetic material a magnetic circuit.

8. An electron discharge device having an envelope including a header member of flat conducting material and an elongated flat anode block mounted normal to said header member and having a plurality of anode elements delining a central space, said anode block having a passageway extending therethrough, said header member having a plurality of apertures extending therethrough and tubular conducting :members extending through said apertures and insulatingly sealed therein to said header and opening into the passageway through said anode block for permitting circulation of a cooling medium through said block, said tubular conducting members insulatingly supporting said anode block from said header member, and a hollow conducting member of rectangular transverse section supported on said header member and surrounding said anode, and an element of magnetic material supported by said hollow conducting member on each side of said anode and adjacent and in registry with said central space, and a cathode for supplying electrons within said central space and supported by one of said elements of magnetic material, and magnetic means registering with said elements of magnetic material and providing therewith a magnetic circuit.

JOHN S. DONAL, JR. BARREMORE B. BROWN. CARMEN LOUIS CUCCIA.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name -Date 2,404,212 Bondley July 16, 1946 FOREIGN PATENTS Number Country Date 389,509 Great Britain Mar. 17, 1933 509,102 Great Britain e- July 11, 1939 

